Editable text controls are inaccessible using API based accessibility

Description

QT4 (and thus VirtualBox) exposes MSAA objects to facilitate accessibility under Windows. However, MSAA does not provide a way to properly work with editable text controls. The biggest problem is that the caret cannot be tracked (i.e. the position of the caret in the text is not exposed), which makes it impossible to cursor through text using only API based accessibility. The solution is to implement support for a richer accessibility API for these controls, such as UI Automation or IAccessible2.

Apparently, QT does have internal support for IAccessible2, but this has not yet been exposed via COM under Windows. This issue needs to be addressed in QT.